Grease nipples are fittings provided on industrial machines that enable additional grease to be supplied to a lubricated moving part of the machine, such as a rolling element bearing. The nipples comprise a nipple head, to which a corresponding grease gun is attached, and a nipple body with a shank that is e.g. screwed into the machine part to be lubricated. To prevent contaminants from clogging up a grease nipple and to prevent their entry into the moving machine part, the nipple head is generally kept covered by a protective cap. In one commercially available type, a first part of the cap fits over and encloses the nipple head, and is removable in order to allow lubrication via the nipple head, while a second part of the cap remains attached to the grease nipple when the nipple head is uncovered. Commonly, the second part of the cap has a hole through which the shank of the grease nipple is inserted, thereby securing the cap to the nipple and preventing the cap from getting lost.
Grease nipples are available in a range of sizes. The diameter of the nipple head can vary, depending on the application and on the size of the grease gun to be used. Furthermore, grease nipples with the same head diameter are available with various shank diameters. Therefore, commercially available caps of the above-described type are usually supplied in sets comprising several pieces in a range of dimensions, whereby the first part of the cap is designed for a particular size of nipple head and the second part of the cap is designed for a particular shank diameter.
Consequently, there is room for improvement in terms of providing a protective cap that is easy to match to various sizes of grease nipple and which lessens the need to carry caps that do not have the right dimensions.